1. Field of the Invention
The present invention relates to a robot programming technique, and more particularly to an offline programming device and an offline programming method, for preparing, in an offline mode, an operation program for making a robot perform a handling operation for a workpiece or a tool with respect to a machine tool. The present invention also relates to a program and a recording medium, for preparing, in an offline mode, an operation program for making a robot perform a handling operation for a workpiece or a tool with respect to a machine tool.
2. Description of the Related Art
In a manufacturing system using a robot (in particular, an industrial robot), a configuration in which a robot is instructed to perform an operation or task for handling a process-related object, such as a workpiece, a tool, etc., relative to a machine tool; for example, loading the object onto a predetermined mount section such as a table, a tool rest, etc.; unloading the object from the mount section; or changing a position or orientation of the object on the mount section is known. In this system configuration, the handling operation can be taught to the robot by an offline programming method that does not use an actual robot or an actual machine tool. Typically, in an offline programming method, the models of the robot and its working environment are provided in a computer, and the robot model is manipulated on a display screen to simulate a desired robot operation, so that position/orientation information and motion sequence information, which are to be taught to the actual robot, are obtained. In this connection, the taught information can be validated by the simulation of the robot operation, and therefore, an optimal operation program can be prepared.
However, the position and orientation of a process-related object adapted to be mounted on a machine tool, such as a workpiece, a tool, etc., in a handling operation for the object performed with respect to a mount section, may be changed in accordance with the contents of a workpiece processing program executed by the machine tool. For example, the positions of a workpiece on a table of the machine tool, in an operation wherein the workpiece is loaded on and unloaded from the table, are commanded as workpiece positions at the time of program starting and program ending, respectively, in a processing program for the workpiece. Also, the orientation of the workpiece in the above workpiece handling operation is determined as an orientation (i.e., a direction of coordinate axes) of a workpiece coordinate system inherently provided in the machine tool (typically, a coordinate system having coordinate axes defined by feed axes of the table or tool rest). Thus, the position and orientation of the workpiece in the workpiece handling operation are determined by a workpiece-position command value described in the workpiece processing program and the inherent machine configuration of the machine tool, and therefore tend to change in accordance with a change in the processing program so as to meet the change of the shape or dimension of an unprocessed or processed workpiece. Such a situation may also occur in the handling operation for a tool with respect to a tool rest in the machine tool.
In order to address the circumstances described above, in a conventional manufacturing system including a machine tool and a robot, in the case where the robot operates in accordance with a handling operation program prepared by an offline programming method, every time the workpiece processing program given to the machine tool is changed, an operator has to modify (or re-teach) the handling operation program by manual labor. In the modification of the operation program, the process-related object such as a workpiece, a tool, etc., is placed on a predetermined mount section of the machine tool at position and orientation in an actual handling operation, in accordance with a workpiece processing program after being changed, and thereafter, an operator manipulates the robot in a manual mode with respect to the process-related object, so as to measure an actual relative positional relationship between the robot and the process-related object. Once the actually measured value of a relative position is obtained, position/orientation information in the handling operation program is automatically modified based on the measured value. In this connection, as a procedure for measuring the relative positional relationship between the robot and the process-related object, a technique for measuring the relative position in a plurality of different orientations of the robot by bringing an end-effector region of the robot closer to the process-related object (see, e.g., Japanese Patent No. 2654206 (JP-B-2654206)), or a technique for three-dimensionally measuring the process-related object at a plurality of different positions by a visual sensor temporarily attached to the robot (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 2005-138223 (JP-A-2005-138223)) is adopted.
As another technique for modifying the operation of a robot in response to the change of a workpiece in a machine tool (i.e., a change in a workpiece processing program), a configuration in which a host computer for controlling the controller of a machine tool and the controller of a robot in an integrated manner is provided in a manufacturing system, and when the workpiece is changed, operation controlling data adapted to a new workpiece is sent from the host computer to the robot controller so as to instruct the robot to perform the handling operation for the new workpiece, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 5-324034 (JP-A-5-324034). According to this technique, it is no longer necessary to manually modify (or re-teach) the operation program given to the robot.
In a manufacturing system wherein a robot performs a handling operation for a workpiece or a tool with respect to a machine tool, the conventional techniques, in which an operator manually modifies a handling operation program in response to the change in a workpiece processing program, may reduce the rate of operation of the manufacturing system due to a measuring operation for obtaining actual data required for the program modification. Also, in order to stably ensure the operating accuracy of the robot following the modified operation program, operator's skill in the above-described measuring operation is required, and labor costs may thus increase. In particular, in the technique using the three-dimensional measurement by the visual sensor, as described in JP-A-2005-138223, equipment costs may increase due to the provision of the visual sensor and an image processing device.
On the other hand, in the configuration in which the host computer is provided in the manufacturing system, as described in JP-A-5-324034, equipment costs also may increase, and in addition, since the operation of the robot may not be optimized through a simulation in connection with the operation controlling data adapted to the new workpiece, it is difficult to improve efficiency, safety and reliability of the manufacturing system.